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author | Anton Vorontsov <avorontsov@ru.mvista.com> | 2010-03-03 08:18:58 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2010-03-04 00:53:53 -0800 |
commit | 0eddba525cf4c3a4aab9feaf36b12b465290d4a7 (patch) | |
tree | b41b9a6ba53635c1c7137bc0993e4c7f03ef721b /drivers/net/gianfar.c | |
parent | 4c020a961a812ffae9846b917304cea504c3a733 (diff) | |
download | kernel_samsung_smdk4412-0eddba525cf4c3a4aab9feaf36b12b465290d4a7.zip kernel_samsung_smdk4412-0eddba525cf4c3a4aab9feaf36b12b465290d4a7.tar.gz kernel_samsung_smdk4412-0eddba525cf4c3a4aab9feaf36b12b465290d4a7.tar.bz2 |
gianfar: Fix TX ring processing on SMP machines
Starting with commit a3bc1f11e9b867a4f49505 ("gianfar: Revive SKB
recycling") gianfar driver sooner or later stops transmitting any
packets on SMP machines.
start_xmit() prepares new skb for transmitting, generally it does
three things:
1. sets up all BDs (marks them ready to send), except the first one.
2. stores skb into tx_queue->tx_skbuff so that clean_tx_ring()
would cleanup it later.
3. sets up the first BD, i.e. marks it ready.
Here is what clean_tx_ring() does:
1. reads skbs from tx_queue->tx_skbuff
2. checks if the *last* BD is ready. If it's still ready [to send]
then it it isn't transmitted, so clean_tx_ring() returns.
Otherwise it actually cleanups BDs. All is OK.
Now, if there is just one BD, code flow:
- start_xmit(): stores skb into tx_skbuff. Note that the first BD
(which is also the last one) isn't marked as ready, yet.
- clean_tx_ring(): sees that skb is not null, *and* its lstatus
says that it is NOT ready (like if BD was sent), so it cleans
it up (bad!)
- start_xmit(): marks BD as ready [to send], but it's too late.
We can fix this simply by reordering lstatus/tx_skbuff writes.
Reported-by: Martyn Welch <martyn.welch@ge.com>
Bisected-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Tested-by: Martyn Welch <martyn.welch@ge.com>
Cc: Sandeep Gopalpet <Sandeep.Kumar@freescale.com>
Cc: Stable <stable@vger.kernel.org> [2.6.33]
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/gianfar.c')
-rw-r--r-- | drivers/net/gianfar.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c index 6aa526e..c3f0619 100644 --- a/drivers/net/gianfar.c +++ b/drivers/net/gianfar.c @@ -2021,7 +2021,6 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev) } /* setup the TxBD length and buffer pointer for the first BD */ - tx_queue->tx_skbuff[tx_queue->skb_curtx] = skb; txbdp_start->bufPtr = dma_map_single(&priv->ofdev->dev, skb->data, skb_headlen(skb), DMA_TO_DEVICE); @@ -2053,6 +2052,10 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev) txbdp_start->lstatus = lstatus; + eieio(); /* force lstatus write before tx_skbuff */ + + tx_queue->tx_skbuff[tx_queue->skb_curtx] = skb; + /* Update the current skb pointer to the next entry we will use * (wrapping if necessary) */ tx_queue->skb_curtx = (tx_queue->skb_curtx + 1) & |